Bleaching paper-pulp.



No. 714,216. Patenid Nov. 25, I902.

' n. c. manzuas.

BLEAGHING PAPER PULP.

(Application filed July 22, 1902-) (No Model.)

UNITED STATES PATENT OFFICE.

ROBERT CHARLES MENZIES, OF MUSSELBURGH, SCOTLAND.

BLEACHING PAPER-PU LP.

SPECIFIGATION forming part of Letters Patent No. 714,216, dated November 25, 1902. Application filed July 22, 1902- Serial No. 116,582. (No specimens.)

."0 at whom, it may concern.-

Be it known that I, ROBERT CHARLES MEN- ZIES, a subject of the King of the United Kingdom of Great Britain and Ireland, residing at Inveresk Paper Mills, Musselburgh, county of Edinburgh, Scotland, have invented certain new and useful Improvements in Bleaching Paper-Pulp or Like Material, (for which application for patent has been made in Great Britain, No. 28, dated January 1, 1902,) of which the following is a specification.

In bleaching paper-pulp in open vessels the bleaching agents employed are commonly in large measure dissipated in fumes or vapor, and a consequently larger portion must be used than is requisite to effect the bleaching process. Moreover, considerable power is expended in the mechanical operation of mixing or incorporating the bleach with the pulp, especially as carried on in breaking-engines or hollanders or like machines.

The object of my invention is to effect the process with a minimum of bleaching agent and with less expenditure of power; and to that end it consists in subjecting the pulp in admixture with the bleaching agent within a closed vessel or vessels to pressure above at mospheric pressure of air or other innocuous gas or of a gas or gaseous mixture having in itself suitable bleaching properties, whereby the reagents employed or the vapors arising from them are prevented from escaping into the atmosphere and are forced into the fiber of the material or caused to more effectually act upon it. During the bleaching process the pulp may be agitated within the closed vessel or vessels; but by preference thorough admixture is obtained by transference'of the material from one vessel to another through connecting-pipes provided with stop-cocks, such transference being efiected by the pressure of the air or gas, which may force the material back and forth through these pipes from a full vessel to an empty one. When the bleaching agent employed is gaseous, it may be forced through the material until the desired pressure is obtained.

The accompanying drawings illustrate in plan at Figure 1 and in elevation at Fig. 2 an arrangement of apparatus suitable for carrying out the bleaching process.

This apparatus comprises a number of fluidtight drums or vessels 0, 0., whose lower ends are contracted and connected at a to a common inlet and'discharge pipe b, fitted with cocks or valves 0. An air or gas compressor dis provided to charge a large air vessel 6, which is connected by a pipe f, having branches f furnished with cocks connected to each vessel a. Another pipe g, connected to the vessels a, serves to discharge these vessels either to the atmosphere at g or to the air-compressor d, as shown.

In carrying out the process the pulp mixed with the bleaching agent is delivered into one or more of the vessels a through the inlet 1) or valve 0. The valve oryalves c is or are closed, and air above atmospheric pressure is forced through the pipes f f into the vessel a, the air-pressure being maintained throughout the bleaching process. v

During the progress of the bleaching operation the valves 0 of any two of the vessels a may be opened, so that by the air-pressure the contents of one vessel are forced through the bottom end of the vessel (1 and upward into an adjoining vessel a, whereby the pulp is agitated and more effectually mixed with the bleach and air or gas. The air or gas from the air vessel e is then applied under pressure to the vessel or, to which the pulp has been transferred.

The transference of the pulp may be effected from vessel to vessel throughout the series, and finally the pulp is discharged into a vat h.

Having now described my invention, what I claim, and desire to secure by Letters Patent, is

The process of bleaching paper-pulp which consists'in subjecting the pulp in admixture with a bleaching agent to pressure of air or gas, above atmospheric pressure, within a closed vessel or vessels and mixing or agitating the material by transference from one vessel to another by means of gaseous pressure.

In witness whereof I have hereunto set my hand in presence of two witnesses.

ROBERT CHARLES MENZIES.

Witnesses:

WALLACE FAIRWEATHER, WALLACE ORANs'roN FAIRWEATHER. 

